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<Title>Boost Graph Library: Transpose Graph</Title>
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<H1><TT>transpose_graph</TT></H1>

<PRE>
template &lt;class <a href="./VertexListGraph.html">VertexListGraph</a>, class <a href="./MutableGraph.html">MutableGraph</a>&gt;
void transpose_graph(const VertexListGraph&amp; G, MutableGraph&amp; G_T,
    const bgl_named_params&lt;P, T, R&gt;&amp; params = <i>all defaults</i>)
</PRE>

<P>
This function computes the transpose of a directed graph. The
transpose of a directed graph <i>G = (V, E)</i>is the graph
<i>G<sup>T</sup> = (V, E<sup>T</sup>)</i> , where <i>E<sup>T</sup> =
{(v, u) in V x V: (u, v) in E}</i> . i.e., <i>G<sup>T</sup></i> is
<i>G</i> with all its edges reversed.  Graph <TT>G_T</TT> passed into
the algorithm must have no vertices and
no edges. The vertices and edges will be added by <tt>transpose_graph()</tt> by
calling <tt>add_vertex</tt> and  <tt>add_edge</tt> as follows for each edge
<i>(u,v)</i> in <tt>G</tt>.

<H3>Example</H3>

Here's an example of transposing a graph:
<a href="../example/transpose-example.cpp"><tt>example/transpose-example.cpp</tt></a>.

<H3>Where Defined</H3>

<P>
<a href="../../../boost/graph/transpose_graph.hpp"><TT>boost/graph/transpose_graph.hpp</TT></a>

<P>

<H3>Parameters</H3>

IN: <tt>const VertexListGraph&amp; G</tt>
<blockquote>
A directed graph. The graph type must be a model of <a href="./VertexListGraph.html">Vertex List Graph</a>.
</blockquote>

OUT: <tt>const MutableGraph&amp; G_T</tt>
<blockquote>
The transposed graph.  The graph type must be a model of <a
href="./MutableGraph.html">Mutable Graph</a>.
</blockquote>

<h3>Named Parameters</h3>

IN: <tt>vertex_copy(VertexCopier vc)</tt>
<blockquote>
This is a <a href="http://www.boost.org/sgi/stl/BinaryFunction.html">Binary Function</a> that copies the properties of a vertex in the original graph
into the corresponding vertex in the copy.<br>

<b>Default:</b> <tt>vertex_copier&lt;VertexListGraph, MutableGraph&gt;</tt>
which uses the property tag <tt>vertex_all</tt> to access a property
map from the graph.
</blockquote>

IN: <tt>edge_copy(EdgeCopier ec)</tt>
<blockquote>
This is a <a href="http://www.boost.org/sgi/stl/BinaryFunction.html">Binary Function</a> that copies the properties of an edge in the original graph
into the corresponding edge in the copy.<br>

<b>Default:</b> <tt>edge_copier&lt;VertexListGraph, MutableGraph&gt;</tt>
which uses the property tag <tt>edge_all</tt> to access a property
map from the graph.
</blockquote>

IN: <tt>vertex_index_map(VertexIndexMap i_map)</tt>
<blockquote>
The vertex index map type must be a model of <a
href="../../property_map/doc/ReadablePropertyMap.html">Readable Property
Map</a> and must map the vertex descriptors of <tt>G</tt> to the
integers from 0 to <tt>num_vertices(G)</tt>.<br>

<b>Default:</b> <tt>get(vertex_index, G)</tt>
    Note: if you use this default, make sure your graph has
    an internal <tt>vertex_index</tt> property. For example,
    <tt>adjacency_list</tt> with <tt>VertexList=listS</tt> does
    not have an internal <tt>vertex_index</tt> property.
</blockquote>


UTIL/OUT: <tt>orig_to_copy(Orig2CopyMap c)</tt>
<blockquote>
This maps vertices in the original graph to vertices in the copy.

<b>Default:</b> an <a
  href="../../property_map/doc/iterator_property_map.html">
  </tt>iterator_property_map</tt></a> created from a
  <tt>std::vector</tt> of the output graph's vertex descriptor type of size
  <tt>num_vertices(g)</tt> and using the <tt>i_map</tt> for the index
  map.
</blockquote>

<H3>Complexity</H3>

<P>
The time complexity is <i>O(V + E)</i>.



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<TABLE>
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<TD nowrap>Copyright &copy; 2000-2001</TD><TD>
<A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>, Indiana University (<A HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>)
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